Childhood Exanthems

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Childhood Exanthems: Introduction - Rash Decisions & Red Alerts

  • Exanthem: Diffuse skin eruption. Enanthem: Mucosal eruption.
  • Key History: Prodrome (nature, duration), fever (pattern, height), contacts (sick, travel), immunization.
  • Rash Morphology: Macular (flat), papular (raised), vesicular (fluid-filled), petechial (non-blanching).
  • Distribution Patterns: Cephalocaudal (head-to-toe), centrifugal (trunk to extremities), centripetal (extremities to trunk).

⭐ Koplik's spots, pathognomonic for measles, are bluish-white spots on an erythematous base on the buccal mucosa, appearing 1-2 days before the rash.

Childhood Exanthems: Measles & Rubella - Dotty Dilemmas & Fever Fits

FeatureMeasles (Rubeola)Rubella (German Measles)
EtiologyParamyxovirusTogavirus
ProdromeFever, 3 C's (Cough, Coryza, Conjunctivitis) 📌; 3-5 daysMild fever, lymphadenopathy; 1-5 days
RashMaculopapular; cephalocaudal; lasts 5-7 days; desquamatesMaculopapular; cephalocaudal; rapid (1-3 days); '3-day measles' 📌
Key SignsKoplik's spots (buccal) Koplik's spots on buccal mucosaForchheimer spots (palate)
ComplicationsOtitis media, pneumonia, encephalitis (SSPE)Arthralgia/arthritis, thrombocytopenia, CRS
PreventionMMR vaccineMMR vaccine

Childhood Exanthems: Parvo B19, HHV-6, VZV - Cheeky Slaps & Rosy Pox

FeatureErythema Infectiosum (Fifth Disease)Roseola Infantum (Sixth Disease)Varicella (Chickenpox)
EtiologyParvovirus B19HHV-6 (Human Herpesvirus 6), HHV-7Varicella-Zoster Virus (VZV)
ProdromeMild fever, malaise, headacheHigh fever (3-5 days), otherwise wellFever, malaise, pharyngitis, anorexia
Rash1. Bright red "slapped cheek" rash
2. Erythematous macular/morbilliform rash on trunk/limbs
3. Lace-like reticular pattern as rash fades
Maculopapular rash appears as fever subsides (exanthem subitum); starts on trunk, spreads to face/extremitiesCrops of intensely pruritic vesicles on erythematous base ("dew drop on rose petal"); various stages present simultaneously; starts on trunk/face, spreads centrifugally
ComplicationsAplastic crisis (in hemolytic anemia), arthralgia/arthritis (adults), hydrops fetalis (pregnancy)Febrile seizuresSecondary bacterial infection, pneumonia, encephalitis, Reye's syndrome (aspirin use ⚠️)

Varicella "dewdrop on rose petal" lesions

⭐ Roseola Infantum (HHV-6/7) is characterized by high fever for 3-5 days in an otherwise well child, followed by rash appearance as the fever abruptly subsides (exanthem subitum).

📌 Varicella = Vesicles in Various stages

Childhood Exanthems: Coxsackie, Strep, Kawasaki - Handfuls & Strawberry Tongues

  • Hand, Foot, Mouth Disease (HFMD):
    • Etiology: Coxsackie A viruses, Enterovirus 71.
    • Rash: Oral ulcers; vesicular lesions on hands, feet, buttocks. Vesicular lesions on palm in Hand Foot Mouth Disease
  • Scarlet Fever:
    • Etiology: Group A Streptococcus (GAS).
    • Rash: Sandpaper texture, Pastia's lines, strawberry tongue, circumoral pallor.
    • Treatment: Penicillin. Scarlet Fever Symptoms
  • Kawasaki Disease:
    • Diagnostic Criteria: Fever (Burn) ≥ 5 days + ≥4 CRASH 📌 (Conjunctivitis, Rash, Adenopathy, Strawberry tongue, Hand/feet changes).
    • Complications: Coronary artery aneurysms.
    • Treatment: IVIG (2g/kg), Aspirin.

⭐ Kawasaki Disease is the leading cause of acquired heart disease in children in developed countries; timely administration of IVIG (ideally within 10 days of fever onset) significantly reduces the risk of coronary artery aneurysms from ~25% to <5%.

High‑Yield Points - ⚡ Biggest Takeaways

  • Measles: Koplik's spots (pathognomonic), cephalocaudal rash, risk of SSPE.
  • Rubella: Forchheimer spots, milder rash, Congenital Rubella Syndrome risk.
  • Erythema Infectiosum (Fifth Disease): Parvovirus B19, "slapped cheeks", then lacy reticular rash.
  • Roseola Infantum: HHV-6/7, high fever then rash post-defervescence.
  • Hand, Foot, Mouth Disease: Coxsackievirus A, oral, palmar, plantar vesicles.
  • Kawasaki Disease: Fever >5 days, mucocutaneous signs, coronary artery aneurysm risk.
  • Scarlet Fever: Group A Strep toxin, sandpaper rash, strawberry tongue, Pastia's lines.

Practice Questions: Childhood Exanthems

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All of the following are true about erythema infectiosum EXCEPT?

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Flashcards: Childhood Exanthems

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What part of the face are commonly involved in pityriasis alba affecting the children?_____

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What part of the face are commonly involved in pityriasis alba affecting the children?_____

Cheeks and around mouth and chin

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